9.40.5.5 literal_position

When using --text-section-literals to place literals inline
in the section being assembled, the .literal_position directive
can be used to mark a potential location for a literal pool.

.literal_position

The .literal_position directive is ignored when the
--text-section-literals option is not used or when
L32R instructions use the absolute addressing mode.

The assembler will automatically place text section literal pools
before ENTRY instructions, so the .literal_position
directive is only needed to specify some other location for a literal
pool. You may need to add an explicit jump instruction to skip over an
inline literal pool.

For example, an interrupt vector does not begin with an ENTRY
instruction so the assembler will be unable to automatically find a good
place to put a literal pool. Moreover, the code for the interrupt
vector must be at a specific starting address, so the literal pool
cannot come before the start of the code. The literal pool for the
vector must be explicitly positioned in the middle of the vector (before
any uses of the literals, due to the negative offsets used by
PC-relative L32R instructions). The .literal_position
directive can be used to do this. In the following code, the literal
for M will automatically be aligned correctly and is placed after
the unconditional jump.